1. Field of the Invention
The present invention relates to a head lamp aiming apparatus for fastening a head lamp to a vehicle body and variably adjusting-the optical axis of the head lamp with respect to the vehicle body, and more particularly to a head lamp aiming apparatus adapted for improving not only the workability of mounting a head lamp on a vehicle body but also the strength of an aiming-adjusting device.
2. Background Art
As shown in FIGS. 11-12, a typical head lamp 50 is constructed so that a lens 53 is fitted into the front opening portion of a lamp body 52 with a concave reflector 51 formed on its rear inner surface in order to form a lamp chamber 54. A bulb 56 is a light source which is fitted into a socket 55 mounted in the rear portion of the lamp body 52 and is supported substantially in the position of a focal point F on the optical axis L of the reflector 51 in the lamp chamber 54. The head lamp 50 is fastened, via an aiming apparatus, to the vehicle body.
The aforesaid aiming apparatus is equipped with a fixed-side bracket 57 having a boss 62 for receiving an aiming-adjusting screw (not shown) for laterally adjusting the optical axis L of the head lamp 50. A fulcrum 58, for pivotally supporting the head lamp 50 on the other side of the lamp body 52, and a fixed-side bracket 60, with a tapping hole 59 for use in screwing an aiming-adjusting screw (not shown), are for vertically adjusting the optical axis L of the head lamp 50. The fixed-side bracket 60 is situated beneath the fulcrum 58.
The bracket 57 has a fitting face 57a and is disposed between the lamp body 52 and a mounting portion of the vehicle body. The bracket 57 is fastened to the vehicle body using at least two fitting holes 61, 61 bored in the fitting face. When the aiming-adjusting screws are turned during the aiming operation, a rotational load is applied to the portion where these fitting holes 61, 61 have been formed. The rotational load not only hastens the deterioration of that portion of the bracket 57 and causes damage thereto, but also lowers the stability of the aiming-adjusting mechanism. Further, a great deal of rotational force is required when the aiming-adjusting screw is first threaded into a tapping hole 63 bored in the boss 62, because the tapping hole 63 is cylindrical. The large rotational force required for tapping the tapping hole 63 may cause damage to the fitting holes 61, 61 and also deteriorate the workability of mounting the head lamp.